The Mass for the Vigil of the Nativity signals a pivot, a change of focus and direction away from Advent where we prepare for the manifestation of God coming to man in Jesus Christ. We now move in this Mass to set our souls to the experience of His manifestation on earth; a manifestation not only at His birth but through His ministry upon the earth for our salvation. Today we set ourselves to experience His ministry to us, as He did for all, from now through Trinity Sunday.